Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators
| Autor: | Kovalev, S., Tielrooij, K. -J., Deinert, J. -C., Ilyakov, I., Awari, N., Chen, Ming, Ponomaryov, A., Bawatna, M., de Oliveira, T. V. A. G., Eng, L. M., Kuznetsov, K. A., Safronenkov, D. A., Kitaeva, G. Kh., Kuznetsov, P. I., Hafez, H. A., Turchinovich, Dmitry, Gensch, M. |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Terahertz
500 Naturwissenschaften und Mathematik::530 Physik::530 Physik Quantentechnologie ultrafast photonics Physics::Optics Quantenmaterialien Topological Insulators Condensed Matter::Materials Science Harmonic Generation topological insulators Ultrafast Ultrafast photonics TA401-492 Surface Science Atomic physics. Constitution and properties of matter Materials of engineering and construction. Mechanics of materials Dirac Material QC170-197 |
| Zdroj: | npj Quantum Materials 6(2021)1, 84 npj Quantum Materials, Vol 6, Iss 1, Pp 1-6 (2021) |
| DOI: | 10.14279/depositonce-17416 |
| Popis: | Topologically protected surface states present rich physics and promising spintronic, optoelectronic, and photonic applications that require a proper understanding of their ultrafast carrier dynamics. Here, we investigate these dynamics in topological insulators (TIs) of the bismuth and antimony chalcogenide family, where we isolate the response of Dirac fermions at the surface from the response of bulk carriers by combining photoexcitation with below-bandgap terahertz (THz) photons and TI samples with varying Fermi level, including one sample with the Fermi level located within the bandgap. We identify distinctly faster relaxation of charge carriers in the topologically protected Dirac surface states (few hundred femtoseconds), compared to bulk carriers (few picoseconds). In agreement with such fast cooling dynamics, we observe THz harmonic generation without any saturation effects for increasing incident fields, unlike graphene which exhibits strong saturation. This opens up promising avenues for increased THz nonlinear conversion efficiencies, and high-bandwidth optoelectronic and spintronic information and communication applications. |
| Databáze: | OpenAIRE |
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